Borehole Directional Survey : Refers to the measurements of the inclinations, azimuths, and specified depths of the stations through a section of borehole. (Bul D20)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}